8. Energy

Question 1

Renewable Energy Source

Answer 1

source of energy that cannot be used up (eg. –hydroelectric, photovoltaic cells, active solar heaters, wind, biofuels)

Question 2

Non-renewable Energy Source

Answer 2

source of energy that can be used up (eg. – coal, oil, natural gas, nuclear)

Question 3

Energy Density (of a fuel)

Answer 3

the ratio of the energy released from the fuel to the mass of the fuel consumed

Question 4

Fossil Fuels

Answer 4

coal, oil, and natural gas

Question 5

Chain Reaction

Answer 5

neutrons released from one fission reaction go on to initiate further reactions

Question 6

Critical Mass

Answer 6

minimum mass of radioactive fuel block needed for a chain reaction to occur

Question 7

Controlled Nuclear Fission

Answer 7

used for power production

Question 8

Uncontrolled Nuclear Fission

Answer 8

used for nuclear weapons

Question 9

Photovoltaic Cell (solar cell, photocell)

Answer 9

converts a portion of the solar radiation directly into a potential difference (voltage) using a semiconductor

Question 10

Albedo (α)

Answer 10

fraction of the total incoming solar radiation received by a planet that is reflected back out into space

Question 11

Greenhouse Effect

Answer 11

Short wavelength radiation received from the Sun causes the Earth’s surface to warm up. Earth will then emit longer wavelength radiation (infra-red) which is absorbed by some gases (eg. - methane, water vapor, carbon dioxide, nitrous oxide) in the atmosphere and re-radiated in all directions. This extra warming of the Earth’s atmosphere is known as the Greenhouse Effect.

Question 12

Global Warming

Answer 12

increase in mean temperature of the Earth in recent years

Question 13

Enhanced (Anthropogenic) Greenhouse Effect

Answer 13

Human activities, mainly related to the burning of fossil fuels, have released extra carbon dioxide into the atmosphere, thereby enhancing or amplifying the greenhouse effect (a possible cause of global warming).

Question 14

Black-Body Radiation

Answer 14

radiation emitted by a “perfect” emitter of radiation

Question 15

Stefan-Boltzmann Law

Answer 15

The total power radiated by a black-body per unit area is proportional to the fourth power of the temperature of the body. (power = σAT4)

Question 16

Emissivity (ε)

Answer 16

ratio of power emitted by an object to the power emitted by a black-body at the same temperature.

Question 17

Surface Heat Capacity (CS)

Answer 17

energy required to raise the temperature of a unit area of a planet’s surface by 1 K. (CS = Q / (A ΔT))